Self-setting calcium phosphate cements (CPC) are promising materials which have a variety of possible medical and dental applications. In situ setting and biocompatibility properties make CPCs potentially useful as endodontic filling materials, as implants for bony defects, and as a binder for other implant materials. CPCs are formed by moistening biphasic mixtures of calcium phosphate salts, usually anhydrous dicalcium phosphate (DCPA) and tetracalcium phosphate (TTCP), with limited amounts of water. Although relatively simple materials in composition, other chemical as well as physical properties, e.g. setting times, porosity and strength, are dependent in a complex manner upon a number of poorly understood parameters associated with the chemistry of the setting process. Particularly relevant are the solution parameters important in establishing the crystalline texture (i.e., size, shape, and aggregation properties) of the apatitic product formed upon completion of the DCPA/TTCP conversion, since the texture of this phase is a major determinant of the mechanical behavior of these cements. Thus, studies of solution influences on apatite crystal growth may prove useful in formulating cements with improved mechanical properties. Presently, the effect of solution supersaturation on apatite growth at pH 7.4 and 37 degrees C is being examined. Results to date suggest that growth of individual apatite crystals is superseded by crystal proliferation as supersaturation increases. This transition from primary growth to secondary nucleation results in a more finely textured apatitic product.